[S2GRAPH-117] Cleaner logging library usage
[S2GRAPH-117] Cleaner logging library usage

JIRA:
    [S2GRAPH-117] https://issues.apache.org/jira/browse/S2GRAPH-117

Pull Request:
    Closes #88

Authors
    Jong Wook Kim: jongwook@nyu.edu

SteamShon/incubator-s2graph,daewon/incubator-s2graph,daewon/incubator-s2graph,SteamShon/incubator-s2graph,SteamShon/incubator-s2graph